Ignition device for ionic valves



Feb. 8, 1949. u. LAMM 2,461,428

IGNITION DEVICE FOR IONIC VALVES Filed April 10, 1947.

* 6/1f0r ....2--' A 39 I U/YO Lam/11 Wow i atented Fei. s, 194d UNITE-Dham IGNITION DEVIGE FOR IONIG'VALVES m Lemm, Llldvika, elcaess sner tomanna ,gvenska Elelgt islga ter s, Sw em, a vm i ation,of,Swe'gilen.aApplication April 10,

Q get, Yas- 194igcsenallnol1740555 the current, and in inverters it maycause the failure of a commutation, which acts vas-a shortcircuit if nospecial protective steps ;;are taken.

For restoring the cathode spot and re-igniting the excitation anode,rapidly acting re-igniting devic h e s wh c Qn rai .,-W th u -m0 l parts.f r insta c r si tanc isnitinadev ce ,s -ea le .isn or or a c iat velma t ones. The present invention relates ,to .,a,d for bringingsuchigniting devices into .;ac tion Vat the disappearance of the cathodespot saidda ic being v ry id and ect ve n ac 'Q 1- The invention isbased on ;the following 013- en/anon. If no cathode spotis p esen iwhenamain anode normally is about, to ;b e, i gnited which means either thatit has just heeo ne positive .or that its potential which already ispositive is admitted by the grid tothe conducting plasma in theneighbourhood of the cathodewe t filid plasma will assume a positive,potential;;-w'thespect to the cathode, often a rather high, potential,as the anodervoltage lrisesgwitho it any ignition taking place. Betweenthe conducting wall of the vessel and the. plasma, therezislasa rule thepossibilityof a ,vivid exchangeofcharges, in the first line by ionattraction andlsecondly by glow discharge which latter eventually maylead to the formation of a cathode spot on,, the wall. The latter maytherefore to ..a certain extent follow the potentialof the plasma whichas aforesaid lies considerably. above that of ":the cathode. to thepresent invention, utilized for feedingfthe instantaneous ignitiondevice either directly or indirectly by operating a rapLdlyacting relay,for instance an ionic tube ithyratron). The direct feeding is generallypreferable ,when the-current between the plasma and the wallissufi'icient to feed the ignitingdevice, sincethe agtion will then bemore rapid and safe. *In'stead'of employing the wall of the vessel,other conductors ingentact vwith the plasma. may-be ,used, as is -;Inore fully explained below.

Three forms of the invention, all arranged for a direct feeding of theigniting device, are diagrammatically illustrated in Figs. 1-5 of theaccompanying drawing.

Fig. 1 shows a single anode high tension valve This potential differenceis, according 8' Claims. ((31:250- 27 .5)

hav n -.,a.-Qathp ia-jeathq e s ace-.2 wit a c nd ct is l ane lqde s a ahas; -P l asula ie wa si ai ie volta ,gii t gibuting conductors 4! andananode 5. Near the cathode, there is h the, a h d lsr ee el e hearl-netted t voltage diyerter lhior -protf: t H A insi a en e th vol agbe -W s ziht -hii 142M11 rathe hi hmnihe p easio o aidturbance.

-The-ar aaselnenfld sc ibed.'o e a esi :-th o1- when th main, anode 1551 e arm-131,5*libfilffi lifldabllfi rennet-ign te the abseneeofializathode spot o cathode, the plasma in the cathode spaceiassumesiazghi-ghqpositive potential. xFor the reasons already statednearly the;same potentialj is .communicatedalso .to the ,wall, ,so vthat a strongcurrent flows irom-athis -wal1- across the valve i 0 tor-the iignitoriil and' thereby produces a new cathode-lspot.

- The-valve w prevents the :ieeding device .9 ofthe ignito-r from;inihiencing;andfrom beinginfiuenced by the potentialoithe wall-=whenimpulses are emitted from=the--saicl---device =9. ---If the valve it -iscomposed of a sufiicient number of dry valve plates -for its purpose, itobtains, at the lncrmal characteristic oi the dry valves, the propertythat the potential difference-"between h Wall andihefiathode wh c i ve lormal, time xdoes:m admi ;an 1 ap r bl vri t sm ,a i ethu ..-a leade 1 9leads h i n imi thedevicafi a aini t d ndih ignitor 8 is only fed fromthe Wall, the alvajll, which? m h lr ga edie ielie et s en e resistanceof directional character, may as shown in Fig. 4 be replaced by avoltage-dependent resistance 42 without any directional character, theohmic value of which decreases with increasing voltage. In certain casesit may consist of an ionic valve. The igniter may also be of acapacitatively acting character.

Instead of deriving the ignition impulse from the potential difierencebetween the wall of the vessel and the cathode, it may also be derivedfrom a conductor inside the vessel of the character of a probe whichalso may serve other purposes. Figs. 2 and 3 show example hereof.

Fig. 2 shows a single-anode valve vessel for comparatively low voltagehaving a cathode l6, anode ll, anode sleeve i8, excitation anode [9 witha current source 29 and an ignitor El with a feeding device 22. In thisform, the ignitor 21 is connected across a valve 23 to a probe 24mounted between the mouth 01 the anode sleeve and the cathode, saidprobe being especially constructed for following the potential of theplasma as closely as possible, for instance provided with points orcoated with an electron emissive substance, and further it may beprovided with a heating device or so placed as to be heated by thesurroundings, whereby it will to a certain extent obtain the characterof a hot cathode. It may at the same time serve as a screen forprotecting the anode against direct radiation from the cathode.

Fig. 3 .shows a polyanodic valve vessel having anodes introduced throughthe bottom. The cathode is designated by 3i, the anodes by- 32 and .theanode sleeves by 331. anode with its current source is not shown. Inpolyanodic vessels, it may be advisable to em ploy a separate conductoror probe for each anode for rapidly absorbing the higher potential whichthe plasma in the neighbourhood of the anode obtains when the cathodespot is extinguished. The anode sleeve itself or a member in theimmediate neighbourhood thereof may be employed. Each such member may beconnected to the ignitor 35 by a separate valve 35. The figure shows theanode sleeves connected in this manner. Instead of using these sleevesas probes, an insulated screen 36 which covers the lower ends thereofand possibly the bottom of the vessel may serve the same purpose.

Fig. shows another form utilizing a thyratron 31, the grid of which isconnected to the wall of the valve vessel through a voltage source 38.Between the anode of the thyratron and the cathode of the main vessel isarranged a voltage source of a type which gives only short impulses.such a source is used because, as is well known, a thyratron circuitcannot be interrupted by grid control only and with a different type ofsource it would be difficult to break the igniter circuit after it wasonce established. The preferred source is a condenser 39 charged from aVoltage source through a high ohmic resistance ll and discharged throughthe thyratron.

I claim as my invention:

1. In ionic valves having an arcing cathode, an

' instantaneously acting igniter permanently adjacent to said cathode, aconductor insulated from said cathode and in contact with the ionizedplasma occupying a current path of said valve, means-controlled by apotential difference between said conductor and said cathode, forforcing a current through said igniter, and means preventing a flow ofcurrent from the cathode to said conductor.

2. In ionic valves having an arcing cathode,

The excitation I an instantaneously acting igniter in contact with saidcathode, a conductor insulated from said cathode and in contact with theionized plasma occupying the current path of said valve, a leadingconnection between said conductor and said igniter, and means preventinga flow of current from the cathode to said conductor.

3. In ionic valves having an arcing cathode, an instantaneously actingigniter in contact with said cathode, a conductor insulated from saidcathode and in contact with the ionized plasma occupying the currentpath of said valve, and a connection including a voltage dependentresistance between said conductor and said igniter.

4. In ionic valves having an arcing cathode, an instantaneously actingigniter in contact with said cathode, a conductor insulated from saidcathode and in contact with the ionized plasma occupying the currentpath of said valve, a device for regularly feeding said igniter, and acommon connection, including a substantially unidirectionally conductingvalve, leading from said conductor to said device and said igniter.

5. In ionic valves having an arcing cathode, an

instantaneously acting igniter in contact with said cathode, aconducting wall insulated from said cathode and surrounding the spaceadjacent to said cathode, and a leading connection between said wall andsaid igniter.

' 6. In ionic valves having an arcing cathode, an instantaneously actingigniter permanently adjacent to said cathode, a conductor screeningdiiierent internal spaces of said valve from each other, and insulatedfrom said cathode, means controlled by a potential difference betweensaid screening conductor and said cathode, for forcing a current throughsaid igniter, and means preventing a flow of current from the cathode tosaid conductor.

7. In ionic valves having an arcing cathode, an instantaneously actingigniter permanently adjacent to said cathode, a conductor screening thespace adjacent to an anode of said valve from other conducting spacesthereof, means controlled by a potential difference between saidconductor and said cathode for forcing a current through said igniter,and means preventing a fiow of current from the cathode to saidconducton.

8. In ionic valves having an arcing cathode, an instantaneously actingigniter permanently adjacent to said cathode, a conductor insulated fromsaid cathode occupying a current path of said valve, means forfacilitating the exchange of electrons between said conductor and theionized plasma, means, controlled by a potential difference between saidconductor and said cathode, for forcing a current through said igniterand cathode, and other means for independently forcing a current throughsaid igniter and cathode.

UNO LAMM.

REFERENCES CITED The following references are of record in the fileofthis patent:

UNITED STATES PATENTS Number Name Date 2,053,437 KnoWles Sept. 8, 19362,144,496 Klemperer Jan. 17, 1939

